Note: Descriptions are shown in the official language in which they were submitted.
CA 02745054 2011-05-30
WO 2010/068218 PCT/US2008/086566
TAPERED SCREW EXTRUSION PROCESS FOR
MAKING SOAP WITH A SECOND PHASE
BACKGROUND OF THE INVENTION
[0001] In recent years, there has been an increasing consumer demand for
aesthetically-
unique soap bars. To make the soap bar more attractive, translucent,
transparent, and
different bar shapes, as well as multiphase and/or multicolored soap bars made
from different
soap materials and/or different colors, have been created to enhance the
attractiveness and
consumer appeal of these products.
[0002] For example, methods and extrusion apparatus to create striated soap
bars have
been shown in United States Patents 3,891,365 and 3,947,200 (both Fischer) and
6,852,260B2 (Vu et al) and to create variegated, multicolored and/or marbled
soap bars have
been described in United States Patents 3,823,215 and 3,940,220 (both
D'Arcangeli).
3,993,722 (Borcher et al), 4,011,170 (Pickin eta!), 6,727,211B1(Aronson eta!),
and
6,805,820B1 (Myers). An injection molding process using two different
components to
produce detergent bars comprising distinct zones has been described in United
States Patent
6,878,319B2 (Browne et al).
BRIEF SUMMARY OF THE INVENTION
[0003] The present invention provides an extrusion process for the
production of a solid
soap product comprising feeding a soap composition into an extruder having a
housing with
an inlet and an outlet and a screw impeller traversing the extruder, wherein
at least a portion
of the housing from the inlet to the outlet of the housing, and ending at the
outlet, is tapered
to form a portion of the housing with a reduced cross-sectional area, and the
screw impeller
extends at least partly into the tapered portion of the extruder, where the
screw impeller ends.
and extruding the soap composition through the extruder.
[0004] The present invention also provides a process for producing a
multiphase bar
soap, comprising: processing a stream comprising a primary soap phase in at
least one refiner
and then into a plodder, comprising a plodder housing, a feed hopper for
receiving material to
be extruded, an extruder, an outlet through which material that has been
extruder exits and an
extruder cone diminishing in cross-section toward and ending at that outlet,
via the feed
hopper, a screw impeller disposed in the extruder and extending at least
partly into the
extruder cone; introducing at least one secondary soap phase into the stream
of the primary
continuous soap phase in the feed hopper of the plodder; and extruding the
stream including
1
CA 02745054 2013-01-09
62301-3034
the primary soap phase and the at-least-one secondary soap phase through the
extruder cone with
the screw impeller within the extrusion region to produce a bar soap having
embedded visually
distinct phases.
BRIEF DESCRIPTION OF THE FIGURES
[0005] FIGURE 1 is a schematic diagram illustrating a conventional
apparatus for
extruding billets that will eventually be cut and pressed into bar soap.
[0006] FIGURE 2 illustrates an embodiment of an apparatus for
extruding bar soap,
which apparatus comprises a dual-stage vacuum plodder including a tapered
screw extending into
the extruder cone, in accordance with certain aspects of the present
teachings.
[0007] FIGURE 3 is a detailed sectional view of the tapered screw within
the extruder
cone region of FIGURE 2.
[0008] FIGURE 3A is a detailed sectional view of the tapered screw
within the extruder
cone region of FIGURE 2 with an inner tapered cone installed inside the
extruder cone.
[0009] FIGURE 4 illustrates another embodiment of an apparatus for
extruding billets of
bar soap, which apparatus comprises a dual-stage vacuum plodder including an
extruder barrel
compartment having a tapered screw extending into the extruder cone and an
extension cone
attached to the extruder cone at the outlet of the extruder cone, in
accordance with certain aspects
of the present teachings.
[0010] FIGURE 5 is a detailed sectional view of the tapered screw
within the extruder
cone and including an extension cone, as shown in FIGURE 4.
[0011] FIGURE 6 illustrates another embodiment of an apparatus for
extruding billets of
bar soap, which apparatus includes a spider device.
[0012] FIGURE 7 is a cross-sectional view of the spider device taken
along line 7-7' of
FIGURE 6.
[0013] FIGURE 8 illustrates yet another embodiment of an apparatus for
extruding soap
billets comprising a soap-finishing line 10C, which apparatus comprises a
single-stage plodder
2
CA 02745054 2013-01-09
62301-3034
including a tapered screw extending into the extruder cone, in accordance with
certain aspects of
the present teachings.
DETAILED DESCRIPTION OF THE INVENTION
[0014] Ranges are used throughout herein in place of describing each
and every value that
is within the range. Any value within the range may be selected for the
parameter being defined.
And all percentage used, unless indicated otherwise, are intended to be
percentages by weight.
[0015] An extrusion apparatus and method have now been developed for
formulating a
2a
CA 02745054 2011-05-30
WO 2010/068218 PCT/US2008/086566
multiphase soap bar, comprising a first phase and at least one additional
phase, where the
additional phase(s) may have similar, or slightly higher hardness compared to
the hardness of
the first phase. In particular, utilizing a tapered screw extending at least
partly into the
extruder cone (frustum) region for manufacturing a multiphase soap bar
produces a better bar
aesthetic with visually distinct phases and/or permits the formation of
desirable marbleized
patterns. The use of such a modified extruder screw design makes the
manufacturing of the
desired bar aesthetic much more feasible, since simple soap formulas may be
used, and no
special processes or complicated equipment is needed for making the soap
phases, especially
for making a harder second soap phase in order that the phases do not
excessively
deform/blend during extrusion.
[0016] Accordingly, an extrusion process is provided for the production of
billets of
multiphase bars of soap, these bars include a continuous primary soap phase
and at least one
secondary solid soap phase embedded therein. The process includes passing a
stream of a
primary continuous soap phase through a first stage of a soap finishing line
that includes a
refiner having one or more roll mills and a plodder. At least one secondary
solid soap phase
is introduced into the stream of the primary continuous soap phase via a feed
hopper/vacuum
chamber later in the plodder design in order to form a combined stream of the
primary
(continuous) and the secondary (discontinuous) soap phases. The stream having
primary and
secondary phases is extruded using a screw with a tapered section extending
into the extruder
cone (frustum) and the stream is formed into billets having embedded visually-
distinct
phases, which billets are subsequently cut and pressed into bars of soap. The
tapered screw is
extended sufficiently into the extruder cone to form an -effective" extrusion
zone in order
that the visually-distinct phases and/or the desirable marbleized patterns are
observed in the
finished bar. This effective extrusion zone is the region between the end of
the tapered screw
and the outlet of the extruder cone. In one embodiment, the inlet
diameter:outlet diameter
ratio is generally up to 3:1. In other embodiments, the ratio is 2.5:1 to 2:1
or 1.5:1 to 1:1.
The inlet diameter is the diameter of the extruder cone at the terminus of the
tapered screw
within the extruder cone and the outlet diameter, measured at the outlet of
the extruder cone
(frustum), becomes the diameter of the extruded soap billet.
[0017] In certain aspects of the invention, the extruder cone optionally
comprises an inner
tapered cone. In another aspect of the invention, the extruder cone optionally
comprises a
smaller extension cone (frustum) attached to the outlet of the extruder cone
through which the
process stream passes. In yet other aspects, the effective extrusion region
further comprises a
3
CA 02745054 2011-05-30
WO 2010/068218 PCT/US2008/086566
spider device, which may be disposed at the terminus of the tapered screw
within the extruder
cone, or may be disposed between the outlet of the extruder cone and the
beginning of the
extension cone, if present.
[0018] As illustrated in FIGURE 2, single-screw and dual-stage (double-
barrel) extruders
for soap bar manufacturing (soap plodders) typically include one or more feed
hoppers, one
(single) or two (dual-stage or duplex) extruder barrels in which one or more
screw impellers
is/are rotatably mounted, and an extruder cone. One or more powdered or
granulated soap
raw materials is/are fed into the apparatus at one end of the barrel, via a
feed hopper, and the
material is then conveyed and compressed by the rotating impeller screw(s)
through the
barrel compartment(s) to the extruder cone (actually a frustum) to produce
soap billets, which
are then cut and pressed into the desired soap bar shape(s).
[0019] In FIGURE 1 (a simplified schematic and omits attendant equipment,
such as
vacuum-producing devices, motors, actuators, and the like), illustrating a
conventional soap
finishing line 10 employing a duplex plodder, a process stream 12, typically
including soap
precursor materials (for example, chips, beads, flakes, chunks, and the like),
color, perfume,
and other ingredients, is introduced to an amalgamator and/or mixer-refiner
14, where the
process stream materials are blended and/or mixed. From 14, the stream is fed
to a roll mill
and/or refiner 16 (optionally a duplex refiner or a simplex refiner, combined
with one or more
roll mills), for further homogenization, then fed into a feed hopper 18 and
into a first (upper)
barrel compartment 22 of a double-barrel (duplex) soap plodder (extruder) 21,
having two
distinct extruder barrel compartments, which plodder compacts or compresses
the stream,
subjecting it to a certain amount of mixing, and moves it from left to right
in the drawing
toward a chamber/connector 23, where the soap may be subjected to a vacuum to
remove any
air bubbles and/or where a coloring agent or dye or other additives may be
added and/or the
soap may be cut into segments before being gravity-fed into a second (lower)
barrel
compartment 24 of the plodder. In this barrel, a rotating screw compacts and
forces the soap
into and through extruder cone (frustum) 28, from which it forms billets,
which billets
optionally enter a cutter 30, where the billets are cut to form discrete soap
bars, and a press 32
for shaping and/or imprinting the cut soap bars. The solid personal
care/laundry/household
cleaning soap bar products 34 then exit the soap-finishing line 10, with the
excess soap
material being recycled by suitable means 36 back to the feed hopper 18 for
reprocessing in
the dual-stage plodder 20.
[0020] When multiphase bar soaps have been manufactured via typical
extruders in soap-
finishing line processes, this production has often involved complex processes
for selecting
4
CA 02745054 2011-05-30
WO 2010/068218
PCT/US2008/086566
and preparing appropriate soap compositions for each phase. For example, in
order to
maintain visually-distinct phases while extruding multiphase bar soaps,
hardness of the
respective phases is selected to facilitate incorporation or embedding of the
second phase into
the first phase, while not excessively blending, mixing, smearing, or
stretching the second
phase within the first phase, in order to achieve a desirable aesthetic. Thus,
in conventional
processes, when extruding bar soap, in which a second phase is embedded within
a first
phase, a second solid phase is often selected to have a significantly higher
hardness as
compared to the primary soap phase, while the secondary phase suitably
withstands various
physical forces associated with the plodding process in the soap plodder in
order to maintain
desirable visually-distinct phases.
[0021] The instant extruder design and extrusion process overcomes the
shortcomings
associated with standard soap extrusion processes for making a multiphase soap
bar, such as
those having a first solid phase and a discrete second solid phase dispersed
therein (e.g., a
translucent, opaque or other second phase). As used herein for convenience, a
multiphase
soap is referred to as having a first continuous phase and a second discrete,
discontinuous
phase dispersed therein, however, the present disclosure contemplates a
plurality of phases in
a solid soap composition. In certain aspects, there are at least two visually-
or
compositionally-distinct phases.
[0022] In accordance with the present disclosure, an extruder in the bar
soap
manufacturing process has a tapered screw extending into the extruder cone
region, to form
an "effective" extrusion zone which has shorter length and a relatively low
ratio of cross-
sectional inlet diameter to outlet diameter in that effective extrusion
region, which eliminates
the key smearing/stretching that conventionally occurs in the plodding
process.
[0023] Processes are provided in accordance with the present teachings that
form solid
soaps by using a plodder and extrusion-supporting devices that enable a wider
selection of
soap material properties and compositions (e.g., phases) and provide an
aesthetically-distinct
and -pleasing multiphase bar soap. As noted above, an extrusion region is
designed to be
shorter and to have a lower ratio of cross-sectional areas of the inlet to the
outlet,
respectively, as compared to conventional designs.
[0024] In certain aspects, an extrusion process for the production of a
solid bar of soap,
comprising a continuous primary soap phase and at least one secondary solid
soap phase
embedded therein, is depicted in the soap-finishing line 10A in Figure 2, the
configuration
and component numbering of which is similar to that of line 10 in FIGURE 1.
The raw
materials of a first primary soap phase are introduced in process stream 12,
which enters an
CA 02745054 2011-05-30
WO 2010/068218 PCT/US2008/086566
amalgamator/mixer refiner 14 and roll mill and/or refiner 16. The process
stream enters
hopper 18 to be fed into a dual stage plodder 20A, having first- and second-
stage/extruder
cylindrical compartments 21. The second-stage screw 26A differs from that the
second screw
26 of Figure 1, as will be discussed in more detail below. The process stream
material (first
primary soap phase materials) exits the first-stage extruder barrel
compartment 22 and enters
into a chamber/connector 23A between the respective extruder compartments 21.
[0025] At least one secondary solid soap phase is introduced via a second
process stream
to the first process stream (primary soap materials) via an inlet 40 in the
chamber/connector
23A to form a combined stream of the primary and secondary soap phases. The
second
process stream may be a liquid or may be in solid form (chips, flakes, beads,
chunks,
particulates, and the like) as it is introduced in chamber/connector 23A. The
physical form of
the second process stream may be selected based upon the desired aesthetics in
the
multiphase solid bar soap. For example, the shape and size of solid secondary
phases are
selected such that they result in desired size, and ultimate visual
effects/aesthetics in the bar
soap, as appreciated by those of skill in the art. Furthermore, the process
may vary from the
apparatus shown in Figure 2, such as, for example, the second process stream
may be injected
in liquid form into various points along the extruder barrel compattment 24A
or extruder
cone 28A in order to achieve different aesthetics upon mixing, for example,
for a marbling
effect. Also, the point of introduction of the secondary soap phase may be at
inlet 18 prior to
entry into the second-stage extruder barrel compartment 24A.
[0026] In one embodiment, there is minimal mixing, stretching, and/or
smearing of the
secondary soap phase during the extrusion process. By minimal it is meant that
two distinct
phases can be viewed in the final soap product by an ordinary observer having
20/20 vision
or corrected to 20/20 vision at a distance of 30 cm.
[0027] The screw impeller shaft 26A forces the mixture of the primary and
secondary
soap phases through an outlet in a extruder cone (frustum) end 44. As noted
above, in
various aspects, the stream is passed through a extruder cone having a tapered
screw
extending thereinto.
[0028] In certain aspects of the present disclosure, the second-stage screw
is modified to
have a tapered screw 26A or an attached tapered screw part at the end of 26A
(not shown),
which extends at least into a portion of the extruder cone, having an
increasingly-reduced
diameter. Thus, rather than having an extruder cone, such as 28 in Figure 1,
the second-stage
screw 26A, or an attached tapered screw part, if present, tapers to a narrower
diameter as it
approaches terminal end 44. However, the extruder cone may further include
other
6
CA 02745054 2011-05-30
WO 2010/068218 PCT/US2008/086566
components, such as an inner cone installed inside the extruder cone, an
extension cone
attached to the terminal end 44 of the extruder cone 28A, or a spider device
installed at the
terminus of the tapered screw inside the extruder cone, or attached at the
connection point
between the extruder cone and extension cone.
[0029] In accordance with various aspects of the present teachings, the
modified second
stage screw 26A shown in FIGURE 2 is shown in more detail in FIGURE 3. The
screw
impeller shaft 26A is designed to move the process stream material through the
second-stage
extruder barrel compartment 24A to the terminal end 44 of the extruder cone,
which results in
an effective extrusion zone with inlet region 52 and material is extruded
through outlet 50.
The effective extrusion zone has a first (inlet) diameter denoted by "a" and a
second diameter
denoted by "b" at outlet 50. The first cross-sectional diameter "a-
corresponds to the point of
the end of the tapered screw 52 the inlet of the effective extrusion zone. The
second cross-
sectional diameter "b- corresponds to the end of the effective extrusion zone
where the soap
billet exits 44, which has the same diameter as the extruded billet. In
various aspects, the
ratio of the inlet and outlet diameters (a:b), also referred to herein as the
inlet diameter to
outlet diameter ratio, is 3 to 1; preferably 2.5 to 1; more preferably 2 to 1;
still more
preferably 1.7 to 1, and in certain aspects, 1.5 or 1 to 1. Such ratios of an
inlet diameter to the
outlet diameter in the extrusion or convergence of soap mixtures into billets,
and ultimately,
soap bars, are particularly desirable, and also applied to the overall
effective extrusion region
(including other components, such as a tapered inner cone, any extension cone
and/or any
spider dies). In the conventional process, this effective extrusion zone
usually has an inlet
diameter to outlet diameter ratio of approximately between 4.5 to 1 and 10 to
I.
[0030] In various aspects, a distance "d" defined by the inlet region 52 to
the outlet 50 is
minimized to be relatively short, as compared to conventional extrusion
equipment. For
example, in certain aspects, "d" is selected to be less than or equal to 200
mm, preferably less
than or equal to 150 mm, optionally less than or equal to 80 mm. In certain
aspects, "d" is 40
to 80 mm, in comparison to conventional extrusion equipment, where it is 450mm
to 650mm.
In this manner, multiphase soap bars made by a process using a plodder
extrusion apparatus
having an effective extrusion zone or convergence zone with a relatively low
inlet diameter to
outlet diameter ratio and/or reduced length between inlet and outlet, provide
an extruded soap
bar billet having an improved aesthetic and further enables the use of a wider
variety of soap
compositions and hardness properties for the respective phases.
[0031] With renewed reference to Figure 2, after exiting the extruder cone
(frustum)
comprising a tapered screw therein, the process stream mixture of primary and
secondary
7
CA 02745054 2013-05-09
62301-3034
phases then passes through cutter 30 and press 32 to form the solid multiphase
soap bars having
the first and second soap phases desirably mixed therein.
[0032] In certain aspects, an extruder cone containing a tapered
screw may further include
an extruder cone 28A installed within it toward the end of the extruder cone,
which similarly
provides an effective extrusion region with suitably low inlet diameter to
outlet diameter ratio,
such as shown in Figures 3A. The soap-finishing line is similar to the
embodiments already
discussed. The inlet diameter to outlet diameter ratio is similar to that
described above. The first
(inlet) diameter "a" occurs at inlet 52, which is compared with a second
(outlet) diameter "b" at an
outlet 50 of the tapered inner cone (frustum). Similarly, the extrusion
section length "d" extends
from inlet 52 to outlet 50.
[0033] In certain aspects, a extruder cone containing a tapered screw
may further include
an extension cone attachment, which similarly provides an effective extrusion
region with suitably
low inlet diameter to outlet diameter ratio, such as shown in Figures 4 and 5.
The soap-finishing
line is similar to the embodiments already discussed (i.e. it shows a soap-
finishing line 10B,
chamber/connector 23B, barrel compartment 24B, tapered screw 26B, extruder
cone 28B), except
that the dual stage vacuum plodder 20B has an extension cone 56 attached to a
terminal end 44B.
The extension cone is optionally coupled to the terminal end 448 via
respectively mating flanges
58, for example. The inlet diameter to outlet diameter ratio is similar to
that described above;
however, the first (inlet) diameter "a" occurs at inlet 52B, which is compared
against a second
(outlet) diameter "b" at an outlet 60 of tapered extension cone (frustum) 56.
Similarly, the
extrusion section length "d" extends from inlet 52B to outlet 60 of the
extension cone 56.
[0034] Figures 6 and 7 show an alternate embodiment of the multiphase
extrusion plodder
device, where the extruder cone 28A further includes a spider attachment
device 62 disposed
between the terminal end 44 of the extruder cone 28A and an extension cone 64.
Spider dies are
well known in the art and an exemplary configuration is shown in Figure 7,
where spider 62 has a
plurality of spokes 68, which converge at 70, forming apertures 72, through
which the process
material flows as it passes from the terminal end 44 of the extruder cone
(frustum) 28A, then
through the extension cone 64 and finally extruded out an outlet 66 of the
extension cone, as
8
CA 02745054 2013-01-09
62301-3034
shown in Figure 6. Thus, the effective extrusion region has an overall ratio
of respective
diameters of the inlet 52 to the outlet 66 of the extension cone, in other
words, a ratio of inlet
diameter to outlet diameter, represented by a:b. Besides its supporting
function for the screw
centralization, it can also used in the present disclosed processes to create
a desired marbleized
pattern. As the process stream passes through apertures 72 of spider device
62,
8a
CA 02745054 2011-05-30
WO 2010/068218 PCT/US2008/086566
certain deformation/flow patterns of the soap material occur, thus enabling
achievement of
the desired aesthetics in the extruded billets and eventual soap bars.
[0035] In certain other aspects, the dual-stage plodder is replaced with a
single-stage
plodder with tapered screw extending at least partly into the extruder cone.
In another aspect,
the dual-stage plodder may also be combined with other devices, such as an
inner cone, an
extension cone and/or a spider device.
[0036] In another embodiment, the tapered screw has at least one groove
extending in a
longitudinal direction within the extruder cone.
[0037] In another embodiment, the at-least-one secondary solid soap phase
includes a
translucent soap.
[0038] In another embodiment, the at-least-one secondary solid soap phase
includes an
opaque soap.
[0039] The multiphase soap billets and bars formed in accordance with the
present
teachings include a continuous phase and a discontinuous phase. Desirably, the
moisture
content of the second phase may be much higher when such a second phase is
used in
accordance with the extrusion processes of the present disclosure, as compared
to such use in
conventional multiphase soap extrusion processes. In one embodiment of the
instant
invention, the translucent soap chip has a typical moisture content of 16% to
18% as
compared to a conventional multiphase soap extrusion process with < 12%
moisture. A
second phase having a higher moisture content typically has a correspondingly-
reduced
hardness value. In another embodiment, a continuous phase and a discontinuous
phase solid
mass are combined in a solid multiphase soap bar, by adding together the
materials for the
respective phases in a mixer at a defined temperature range (35 to 55 C, or 38
to 45 C),
followed by extruding and molding to form the final billets.
Continuous Solid Soap Phase
[0040] The bar composition comprises 55 to 99% of the continuous phase, in
another
embodiment 75 to 95%, and in still another embodiment 80 to 90%.
[0041] The continuous phase includes a surfactant or detergent base
suitable for cleansing
the skin and optionally a plasticizing agent used to control its consistency.
Discontinuous Phase
100421 The discontinuous phase may represent 1 to 35% of the bar in one
embodiment, 5
to 25% in another embodiment, and 10 to 20% in yet another embodiment. It is
generally the
shape, distribution and surface quality (e.g., how visually distinctive) of
the discontinuous
phase that gives the bar a pleasing visual aesthetic, and in certain aspects,
an artisan-crafted
9
CA 02745054 2011-05-30
WO 2010/068218
PCT/US2008/086566
quality.
[0043] In
certain aspects, the discontinuous phase domains of the solid multiphase soap
bar may have a variety of shapes. For example, the domains may appear in cross-
section to
approximate oblate or prolate spheroids, disks, cylinders, prisms, rhomboids,
cubes or
crescents, or they may have irregular shapes. In certain aspects, such
discontinuous phase
domains have a longest dimension of 3 to 70 millimeters in length, in others 5
to 50, and in
still others 5 to 35 millimeters. As discussed above, the discontinuous phase
domain is
optionally introduced via liquid injection of the discontinuous phases, which
may create
ribbons, stripes, marbling, and the like.
[0044]
Further, either the continuous or discontinuous phase may be made
multicolored,
e.g., marbleized, through the judicious use of coloring agents/dyes, as is
well known in the
art.
